Villas-Boas hopes to sign a new striker to play alongside Defoe, rather than replace the England ace.
He said: "Well one thing that's positive is that whenever we get our strikers back, I think Jermain [Dafoe] is coming back to training in London and we will respect his personal tragedy with the most amount of time that he thinks he is entitled.
"On the other front, we look positive because as soon as we get the striker that we want it will make us stronger in training and make us stronger in a match situation. Its not an ideal situation because we are delaying our preparation in some way, but strikers of the obvious quality that we are looking for will certainly add to us. It will take them time to reach physically the condition that we are in but that quality will be in discussion."